Question : The angle of depression of a point situated at a distance of 70 m from the base of a tower is $60^{\circ}$. The height of the tower is:

Question : A pilot in an aeroplane at an altitude of 200 metres observes two points lying on either side of a river. If the angles of depression of the two points be $45^{\circ}$ and $60^{\circ}$, then the width of the river is:

Question : The tower is 50 metres high, its shadow is $x$ metres shorter when the sun's elevation is $45°$ than when it is $30°$. The value of $x$ (in metres) is:

Question : The value of the following is:
$\frac{\left (\tan20^{\circ} \right )^{2}}{\left (\operatorname{cosec70^{\circ}} \right )^{2}}+\frac{\left (\cot20^{\circ} \right )^{2}}{\left (\sec70^{\circ} \right )^{2}}+2\tan15^{\circ}  \tan45^{\circ} \tan75^{\circ}$

Question : If $A=30^{\circ}$, then find the value of $\frac{(2 \tan A)}{\left(1-\tan^2 A\right)}$.